As a structure for joining together different types of materials, Patent Document 1 (Japanese Patent Application Laid-Open (JP-A) No. 2010-207898) discloses a structure in which an aluminum alloy member and a steel member are joined together by welding a rivet made of a ferrous metal and the steel member together in a state in which a shaft of the rivet has been made to penetrate the aluminum alloy member, and a head of the rivet remains at an outer surface of the aluminum alloy member. Note that Patent Document 2 (JP-A No. 2005-119577) discloses a structure in which a roof panel made of an aluminum alloy and a roof side rail made of a ferrous metal are joined together by a non-penetrating rivet, and the roof side rail is configured by a high tensile strength steel sheet.
In the structure disclosed in Patent Document 1 (JP-A No. 2010-207898), the head of the rivet made of a ferrous metal is exposed at the outer surface of the aluminum alloy member, and so there is a possibility that electrolytic corrosion (also referred to as galvanic corrosion) due to water ingress might occur at a location where the rivet is provided on the vehicle exterior of a vehicle.